TW201720865A - Thermoplastic resin composition and molding product made therefrom - Google Patents

Abstract

A thermoplastic resin composition and a molding product made therefrom are provided. The thermoplastic resin composition includes a branched copolymer and a rubber modified styrene series resin. The branched copolymer includes a tetrathiol compound unit, a styrene series monomer unit, and an acrylonitrile series monomer unit. The rubber modified styrene series resin includes 70 to 90 weight% of styrene series copolymer as a continuous phase and 10 to 30 weight% of rubber particle as a dispersed phase, wherein the styrene series copolymer includes first and second styrene-acrylonitrile series copolymers whose weight average molecular weight are different. Based on 100 weight% of the total content of the first and the second styrene-acrylonitrile series copolymers, the content of the first styrene-acrylonitrile series copolymer is from 45 to 55 weight%, the content of the second styrene-acrylonitrile series copolymer is from 45 to 55 weight%.

Description

Thermoplastic resin composition and molded article thereof

The present invention relates to a resin composition, and more particularly to a thermoplastic resin composition and a molded article formed therefrom.

Thermoplastic resins such as styrenic resins have been commonly used in various fields such as home appliances, mechanical parts, office supplies, electronic components, or the automotive industry. Among them, since the surface of the molded article obtained by the styrene resin is uniform in gloss, the appearance is very beautiful, and it is often used for the appearance of the product.

Conventional thermoplastic resin processing methods such as injection molding, extrusion molding, or blow molding can shape the thermoplastic resin. In addition, there are special processing methods such as vacuum forming, in which the resin is first pressed into a sheet, and then heated and softened, and the desired molded article is formed by vacuum pressure; wherein the difficulty of the board is The shear viscosity of the resin itself is generally low, and the shear viscosity is low, which helps the forming of the sheet; in addition, the vacuum formability is related to the elongational viscosity of the resin itself. The high elongational viscosity means that the film is easily stretched and deformed during molding, and the moldability is improved.

In the prior art, it is known that the shear viscosity and elongational viscosity of a thermoplastic resin can be improved by adding a small amount of a linear copolymer or a branched copolymer, but once the amount of addition is excessive, because of the thermoplasticity The shear viscosity of the resin cannot be reduced, which in turn affects the characteristics of the plate. Therefore, how to make the thermoplastic resin have high elongational viscosity and low shear viscosity at the same time is a problem to be solved.

The present invention provides a thermoplastic resin composition and a molded article formed from the above composition, which simultaneously increases the elongational viscosity and lowers the shear viscosity thereof, and at the same time, the sheeting property and the vacuum moldability.

A thermoplastic resin composition of the present invention comprises a divergent copolymer and a rubber-modified styrene resin. The dicromeric copolymer includes a tetrathiol compound unit, a first styrene monomer unit, and a first acrylonitrile monomer unit. The rubber-modified styrene-based resin comprises a continuous phase formed by 70% by weight to 90% by weight of a styrene-based copolymer and a dispersed phase formed by 10% by weight to 30% by weight of rubber particles, wherein the styrene-based copolymerization The first styrene-acrylonitrile copolymer and the second styrene-acrylonitrile copolymer, the weight average molecular weight of the first styrene-acrylonitrile copolymer and the second styrene-acrylonitrile copolymer The weight average molecular weights are different. The content of the first styrene-acrylonitrile-based copolymer is from 45% by weight to 55% by weight based on the total content of the first styrene-acrylonitrile-based copolymer and the second styrene-acrylonitrile-based copolymer of 100% by weight. The content of the second styrene-acrylonitrile-based copolymer is from 45% by weight to 55% by weight.

In one embodiment of the present invention, the first styrene-acrylonitrile-based copolymer has a weight average molecular weight of, for example, 180,000 to 240,000, and the second styrene-acrylonitrile-based copolymer has a weight average molecular weight of, for example, 110,000 to 17 Million.

In an embodiment of the invention, the first styrene-acrylonitrile-based copolymer comprises 71% by weight to 74% by weight of the second styrene monomer unit and 26% by weight to 29% by weight of the second acrylonitrile. The monomer unit, the second styrene-acrylonitrile-based copolymer contains 60% by weight to 69% by weight of the third styrene monomer unit and 31% by weight to 40% by weight of the third acrylonitrile monomer unit.

In one embodiment of the present invention, the content of the above-mentioned branched copolymer is from 1 part by weight to 10 parts by weight based on 100 parts by weight of the rubber-modified styrene resin.

In one embodiment of the present invention, the content of the above-mentioned branched copolymer is from 1.5 parts by weight to 8 parts by weight based on 100 parts by weight of the rubber-modified styrene resin.

In one embodiment of the present invention, the content of the above-mentioned branched copolymer is from 2.5 parts by weight to 6 parts by weight based on 100 parts by weight of the rubber-modified styrene resin.

In an embodiment of the invention, the divergent copolymer has an average radius of gyration of from 75 nm to 110 nm.

In an embodiment of the invention, the divergent copolymer has an average radius of gyration of from 80 nm to 100 nm.

In an embodiment of the invention, the above-mentioned branched copolymer has a weight average molecular weight of 1,000,000 to 7,000,000.

In an embodiment of the invention, the above-mentioned branched copolymer has a weight average molecular weight of 2,000,000 to 5,000,000.

In an embodiment of the invention, the tetrathiol compound unit is formed of a tetrathiol compound.

In an embodiment of the invention, the tetrathiol compound is selected from the group consisting of pentaerythritol tetrakis (3-mercapto propionate) and tetrakis(2-mercaptoacetic acid) pentaerythritol [pentaerythritol tetrakis (2) -mercapto ethanate)], pentaerythritol tetrakis (4-mercapto butanate), pentaerythritol tetrakis (5-mercapto pentanate), and tetra (4-mercapto butanate) At least one of the group consisting of: 6-mercapto hexanate; 6-mercapto hexanate.

In one embodiment of the present invention, the above tetrathiol compound is, for example, pentaerythritol tetrakis (3-mercapto propionate).

The molded article of the present invention is formed of the thermoplastic resin composition as described above.

Based on the above, the thermoplastic resin composition of the present invention contains a divergent copolymer and a rubber-modified styrene-based resin, and the styrene-based copolymer in the rubber-modified styrene-based resin contains a weight average molecular weight which is different. First and second styrene-acrylonitrile-based copolymers, wherein the total content of the first and second styrene-acrylonitrile-based copolymers is 100% by weight, and the content of the first styrene-acrylonitrile-based copolymer The content of the second styrene-acrylonitrile-based copolymer is from 45% by weight to 55% by weight, so that the obtained molded article can reduce the elongation while reducing the shearing thereof. Viscosity is not only suitable for general plate forming, but also for special processing methods such as vacuum forming.

The above described features and advantages of the present invention will be more apparent from the following description.

Hereinafter, embodiments of the invention will be described in detail. However, these embodiments are illustrative, and the disclosure of the present invention is not limited thereto.

In an embodiment of the invention, the thermoplastic resin composition comprises a divergent copolymer and a rubber-modified styrene resin. Wherein the divergent copolymer comprises a tetrathiol compound unit, a first styrene monomer unit, and a first acrylonitrile monomer unit; and the rubber modified styrene resin comprises a continuous phase styrene copolymer The rubber particles with the dispersed phase further comprise, in the styrene-based copolymer, a first styrene-acrylonitrile copolymer having a weight average molecular weight and a second styrene-acrylonitrile copolymer, and based on the first The total content of the styrene-acrylonitrile-based copolymer and the second styrene-acrylonitrile-based copolymer is 100% by weight, and the content of the first styrene-acrylonitrile-based copolymer is 45% by weight to 55% by weight, second The content of the styrene-acrylonitrile-based copolymer is from 45% by weight to 55% by weight.

On the other hand, in the thermoplastic resin composition of the present embodiment, the content of the condensed copolymer is, for example, 1 part by weight to 10 parts by weight based on 100 parts by weight of the rubber-modified styrene-based resin, and is divergent. The more the content of the copolymer, the higher the elongational viscosity and the shear viscosity. Preferably, the content of the conjugated copolymer is from about 1.5 parts by weight to about 8 parts by weight, and more preferably, the content of the condensed copolymer. It is about 2.5 parts by weight to 6 parts by weight.

The present embodiment will be described below, but the present invention is not limited thereto.

Source of divergent copolymer

The tetrathiol compound unit contained in the branched copolymer of the present embodiment may be formed of a tetrathiol compound, for example, by removing a hydrogen on a thiol group from a tetrathiol compound, and The tetrathiol compound is, for example, selected from the group consisting of pentaerythritol tetrakis (3-mercapto propionate), pentaerythritol tetrakis (2-mercapto ethanate), and tetrakis(4-mercapto propionate). (4-mercaptobutyric acid) pentaerythritol [pentaerythritol tetrakis (4-mercapto butanate), tetrakis(5-mercaptopentanoic acid) pentaerythritol [pentaerythritol tetrakis (5-mercapto pentanate)] and tetrakis (6-mercaptohexanoic acid) At least one of the groups consisting of pentaerythritol tetrakis (6-mercapto hexanate); wherein tetrakis(3-mercaptopropionic acid) pentaerythritol is preferred.

Further, the first styrene monomer unit contained in the branched copolymer is, for example, a styrene monomer unit; and the first acrylonitrile monomer unit is, for example, an acrylonitrile monomer unit. Here, the monomer unit means a structural unit formed by copolymerization of a first styrene monomer or a first acrylonitrile monomer.

The above first styrenic monomers may be used singly or in combination, and the first styrenic monomers include, but are not limited to, styrene, α-methylstyrene, p-tert-butylstyrene, p-methylbenzene. Ethylene, o-methyl styrene, m-methyl styrene, 2,4-dimethyl styrene, ethyl styrene, α-methyl-p-methyl styrene or bromostyrene. Preferably, the first styrenic monomer is styrene, alpha-methyl styrene, or a combination thereof.

The above first acrylonitrile-based monomer may also be used singly or in combination, and the first acrylonitrile-based monomer includes, but is not limited to, acrylonitrile or α-methacrylonitrile. Preferably, the first acrylonitrile monomer is acrylonitrile.

The divalent copolymer of this embodiment can be prepared by a conventional method known in the art to which the present invention pertains, such as emulsion polymerization, bulk (bulk) polymerization, suspension polymerization, and solution polymerization, to obtain a bifurcated copolymer. The average radius of gyration is, for example, between 75 nm and 110 nm, more preferably between 80 nm and 100 nm; the weight average molecular weight is, for example, between 1,000,000 and 7 million, more preferably 2 to 5 million between.

Source of rubber modified styrene resin

In the rubber-modified styrene-based resin of the present embodiment, the weight average molecular weight of the first styrene-acrylonitrile-based copolymer in the styrene-based copolymer for forming the continuous phase is, for example, between 180,000 and 240,000. The weight average molecular weight of the second styrene-acrylonitrile-based copolymer is, for example, between 110,000 and 170,000. The rubber particles forming the dispersed phase are, for example, a rubber polymer and a graft copolymer grafted onto the rubber polymer, such as a rubber graft copolymer. The rubber-modified styrene-based resin in the present embodiment may be, for example, a graft-kneading method in which the styrene-based copolymer and the rubber component (such as a rubber graft copolymer) are in a dry state in a biaxial state. Made by the machine.

< First styrene - Acrylonitrile copolymer >

In the present embodiment, the first styrene-acrylonitrile-based copolymer contains, for example, 71% by weight to 74% by weight of the second styrene-based monomer unit, and 26% by weight to 29% by weight of the second acrylonitrile-based single sheet. Body unit. Here, the monomer unit means a structural unit formed by copolymerization of a second styrene monomer or a second acrylonitrile monomer.

In detail, in one embodiment, the preparation method of the first styrene-acrylonitrile-based copolymer is not particularly limited, and may be a solution copolymerization method, a bulk copolymerization method, an emulsion copolymerization method, or a suspension copolymerization method which are generally used. Etc., preferably solution copolymerization or bulk copolymerization. The reactor used in the foregoing reaction may be one of a fully mixed continuous reactor (CSTR), a column flow reactor (PFR), or a static mixing reactor or Different kinds of combinations. Taking solution copolymerization as an example, the first styrene-acrylonitrile copolymer is produced by solution copolymerization by a monomer component including a second styrene monomer and a second acrylonitrile monomer. be made of. However, the invention is not limited thereto. In another embodiment, the first styrene-acrylonitrile-based copolymer may be prepared by including a second styrene monomer, a second acrylonitrile monomer, and a first other copolymerizable monomer. The monomer component is obtained by solution copolymerization.

The second styrenic monomer may be used singly or in combination, and the second styrenic monomer includes, but is not limited to, styrene, α-methyl styrene, p-t-butyl styrene, p-methyl styrene. , o-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, α-methyl-p-methylstyrene or bromostyrene. Preferably, the second styrenic monomer is styrene, alpha-methyl styrene, or a combination thereof. Further, the total amount of the second styrene-based monomer, the second acrylonitrile-based monomer, and the first other copolymerizable monomer is 100% by weight, and the content of the second styrene-based monomer is, for example, 50% by weight. Up to 90% by weight; preferably from 55% by weight to 85% by weight; more preferably from 58% by weight to 80% by weight.

The second acrylonitrile-based monomer may also be used singly or in combination, and the second acrylonitrile-based monomer includes, but is not limited to, acrylonitrile or α-methacrylonitrile. Preferably, the second acrylonitrile monomer is acrylonitrile. Further, the total amount of the second acrylonitrile-based monomer is 100% by weight based on the total amount of the second styrene-based monomer, the second acrylonitrile-based monomer, and the first other copolymerizable monomer, and the content of the second acrylonitrile-based monomer is, for example, 10% by weight. Up to 50% by weight; preferably 15% by weight to 45% by weight; more preferably 20% by weight to 42% by weight.

The first other copolymerizable monomers may be used singly or in combination, and the first other copolymerizable monomers include, but are not limited to, acrylic monomers, methacrylic monomers, acrylate monomers, methacrylate monomers. Monofunctional maleic imine monomer, ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, vinyl chloride, vinylidene chloride, Tetrafluoroethylene, vinyl chloride fork, chlorotrifluoroethylene, hexafluoropropylene, butadiene, propenylamine, isobutenylamine, vinyl acetate, ethyl vinyl ether (ethyl Vinyl ether), methyl vinyl ketone, anhydrous maleic acid, cis-methylbutenedioic acid or anhydrous methyl fumaric acid (trans- Methylbutenedioic acid) and so on. In detail, acrylic monomers include, but are not limited to, acrylic acid. The methacrylic monomers include, but are not limited to, methacrylic acid. Acrylate monomers include, but are not limited to, methyl acrylate, ethyl acrylate, isopropyl acrylate, or butyl acrylate. Preferably, the acrylate monomer is butyl acrylate. Methacrylate monomers include, but are not limited to, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, benzyl methacrylate, hexyl methacrylate, methyl Cyclohexyl acrylate, dodecyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate , ethylene dimethacrylate, or neopentyl dimethacrylate. The above monofunctional maleimide-based monomer means that the monomer contains only a single maleimine functional group. The above monofunctional maleimide-based monomers may be used singly or in combination, and the monofunctional maleimide-based monomers such as, but not limited to, maleic imine, nitrogen-methyl maleimide, Nitrogen-isopropylmaleimide, nitrogen-butyl maleimide, nitrogen-hexylmaleimide, nitrogen-octyl maleimide, nitrogen-dodecylmalamine Amine, nitrogen-cyclohexylmaleimide, N-phenylmaleimide (PMI), nitrogen-2-methylmaleimide, nitrogen-2,3-dimethyl Phenylphenylmaleimide, nitrogen-2,4-dimethylphenylmaleimide, nitrogen-2,6-dimethylphenylmaleimide, nitrogen-2,3-di Ethylphenylmaleimide, nitrogen-2,4-diethylphenylmaleimide, nitrogen-2,3-dibutylphenylmaleimide, nitrogen-2,4- Dibutylphenylmaleimide, nitrogen-2,3-dichlorophenylmaleimide, nitrogen-2,4-dichlorophenylmaleimide, nitrogen-2,3-di Bromophenylmaleimide or nitrogen-2,4-dibromophenylmaleimide or the like. Preferably, the above monofunctional maleimide-based monomer is, for example, nitrogen-phenylmaleimide. Further, preferably, the first other copolymerizable monomer may be selected from methyl methacrylate, butyl methacrylate, a monofunctional maleimide monomer, or a combination thereof. Further, based on the total amount of the second styrene monomer, the second acrylonitrile monomer, and the first other copolymerizable monomer being 100% by weight, the content of the first other copolymerizable monomer is, for example, 0 weight. From 40% by weight to 40% by weight; more preferably from 0% by weight to 30% by weight; more preferably from 0% by weight to 22% by weight.

Further, in the solution copolymerization, a solvent such as benzene, toluene, ethylbenzene, p-xylene, o-xylene, m-xylene, pentane, octane, cyclohexane, methyl ethyl ketone, acetone or methyl ketone is used. . The solvent is used in an amount of, for example, 0 to 40 parts by weight, preferably 5 to 35 parts by weight, based on 100 parts by weight of the reactant.

Further, in the solution copolymerization reaction, a polymerization initiator may be optionally added. The polymerization initiator is used in an amount of, for example, 0 to 1 part by weight, preferably 0.001 to 0.5 part by weight, based on 100 parts by weight of the reactant.

In detail, the polymerization initiator may include a monofunctional polymerization initiator, a polyfunctional polymerization initiator, or a combination thereof. The monofunctional polymerization initiators may be used singly or in combination, and the monofunctional polymerization initiators include, but are not limited to, benzoyl peroxide, dicumyl peroxide, T-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxybenzoate T-butyl-peroxy benzoate), bis-2-ethylhexyl peroxy dicarbonate, tert-butyl peroxy isopropyl carbonate BPIC), cyclohexanone peroxide, 2,2'-azo-bis-isobutyronitrile (AIBN), 1,1'-azobicyclo 1,1'-azo-biscyclohexane-1-carbonitrile, or 2,2'-azo-bis-2-methylbutyronitrile (2,2'-azo-bis-2 -methyl butyronitrile), wherein benzammonium peroxide and 2,2'-azo-bis-isobutyronitrile are preferred.

The polyfunctional polymerization initiators may also be used singly or in combination, and the polyfunctional polymerization initiators include, but are not limited to, 1,1-bis-tert-butylperoxycyclohexane (1,1-bis-). T-butyl peroxy cyclohexane (TX-22), 1,1-bis-tert-butylperoxy-3,3,5-trimethylcyclohexane (1,1-bis-t-butylperoxy-3, 3,5-trimethyl cyclohexane, referred to as TX-29A), 2,5-dimethyl-2,5-bis-(2-ethylperoxyhexane)hexane (2,5-dimethyl-2,5- Bis-(2-ethylhexanoxy peroxy)hexane), 4-(t-butylperoxycarbonyl)-3-hexyl-6-[7-(t-butylperoxycarbonyl)heptyl]cyclohexane (4- (t-butyl peroxy carbonyl)-3-hexyl-6-[7-(t-butyl peroxy carbonyl)heptyl] cyclohexane), di-t-butyl-diperoxyazelate , 2,5-Dimethyl-2,5-bis(benzoyl peroxy)hexane, di-third Di-t-butyl peroxy-hexahydro-terephthalate (BPHTH), or 2,2-bis(4,4-di-t-butylperoxy)cyclohexyl Propane (2,2-bis-(4,4-di-t-but) Yl peroxy)cyclohexyl propane, referred to as PX-12).

Further, in the solution copolymerization reaction, a chain transfer agent may be selectively added. The chain transfer agent may be used singly or in combination, and the chain transfer agent includes, but is not limited to: (1) a mercaptan compound: methyl mercaptan, n-butyl mercaptan, cyclohexyl mercaptan, n- thirteen N-dodecyl mercaptan (NDM), stearyl mercaptan, t-dodecyl mercaptan (TDM), n-propyl mercaptan , n-octyl mercaptan, tri-octyl mercaptan, tri-decyl mercaptan, pentaerythritol tetrakis (3-mercapto propionate), isova Pentaerythritol tetrakis (2-mercapto ethanate), pentaerythritol tetrakis (4-mercapto butanate), pentaerythritol Pentaerythritol tetrakis (5-mercapto pentanate), pentaerythritol tetrakis (6-mercapto hexanate), tri-(2- Trimethylolpropane tris (2-mercapto ethanate), tris-(3-mercaptopropionic acid) trimethylolpropyl ester (trime) Thylolpropane tris (3-mercapto propionate), referred to as TMPT), or trimethylolpropane tris (6-mercapto hexanate), etc.; (2) alkyl amines Compound: monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, monobutylamine, di-n-butylamine, or tri-n-butylamine; 3) Other chain transfer agents: pentaphenylethane, α-methyl styrene dimer or terpinolene. Preferably, the chain transfer agent is selected from n-dodecyl mercaptan, tertiary dodecyl mercaptan, tris-(3-mercaptopropionic acid) trimethylol propyl ester, or the like combination. Further, the chain transfer agent is used in an amount of, for example, 0 to 2 parts by weight, preferably 0.001 to 1 part by weight, based on 100 parts by weight of the reactant.

Further, the operating temperature range of the solution copolymerization is, for example, 70 ° C to 140 ° C, preferably 90 ° C to 130 ° C.

< Second styrene - Acrylonitrile copolymer >

In the present embodiment, the preparation method and source of the second styrene-acrylonitrile-based copolymer are substantially the same as those of the first styrene-acrylonitrile-based copolymer, with the difference that the second styrene-acrylonitrile-based copolymer contains, for example. 60% by weight to 69% by weight of the third styrenic monomer unit, and 31% by weight to 40% by weight of the third acrylonitrile monomer unit. Here, the monomer unit means a structural unit formed by copolymerization of a third styrene monomer or a third acrylonitrile monomer. The third styrene monomer may be selected from the monomers listed in the second styrene monomer alone or in combination; the third acrylonitrile monomer may be from the second acrylonitrile monomer. One of the listed monomers is used singly or in combination of several.

< Rubber graft copolymer >

The rubber-grafted copolymer of the rubber-modified styrene resin of the present embodiment can be obtained by graft polymerization of a rubber polymer and a copolymerizable monomer component. The rubber polymer is, for example but not limited to, a diene rubber, a polyacrylate rubber or a polyoxyalkylene rubber. Among them, a diene rubber is preferred, and it may be used singly or in combination.

For example, the rubber graft copolymer may be a rubber polymer (solid content), a monomer component containing a styrene monomer and an acrylonitrile monomer, and an optionally added emulsifier, polymerization initiation. Additives such as a reagent or a chain transfer agent are obtained by graft polymerization.

The rubber graft copolymer of the present embodiment may be obtained by graft polymerization of 2 parts by weight to 90 parts by weight of a diene rubber, and 98 parts by weight to 10 parts by weight of a monomer mixture, wherein The monomer mixture may be 100 parts by weight, and the monomer mixture may include 40 parts by weight to 90 parts by weight of the fourth styrene monomer, 60 parts by weight to 10 parts by weight of the fourth acrylonitrile monomer, and 0 part by weight. And 40 parts by weight of a second other copolymerizable monomer, optionally selected; which can be obtained by polymerization by bulk, solution, suspension or emulsion polymerization, respectively, or can be obtained by a combination of these polymerization methods, For example, an emulsification-block or block-suspension polymerization method is preferred as an emulsion polymerization method, a bulk polymerization method, and a solution polymerization method.

The method for producing a rubber graft copolymer obtained by emulsion polymerization may be grafted in a presence of from 2 parts by weight to 90 parts by weight (dry weight) of the diene rubber emulsion, and from 98 parts by weight to 10 parts by weight of the monomer mixture. The emulsion obtained by polymerizing the rubber particles having a weight average particle diameter of 0.05 μm to 0.8 μm is obtained by a step of coagulation, dehydration, drying, and the like. The rubber graft copolymer obtained by the above emulsion polymerization method has a rubber content of usually 25% by weight to 90% by weight, preferably 45% by weight to 80% by weight.

The above diene rubber may be used singly or in combination, such as, but not limited to, butadiene rubber, butadiene-styrene rubber, butadiene-acrylonitrile rubber or butadiene-methacrylonitrile rubber, and the like. It is a butadiene rubber which can be directly polymerized into a weight average particle diameter of 0.05 μm to 0.8 μm, or can be first polymerized into a small particle size rubber emulsion of 0.05 μm to 0.18 μm, and then subjected to a conventional rubber fat method. a rubber emulsion of a small particle size of 0.05 μm to 0.18 μm is formed into a rubber emulsion of 0.2 μm to 0.8 μm, and the rubber fat method may be a chemical fertilizer method of adding an organic acid or a metal salt or a polymer aggregating agent containing a carboxylic acid group. Mechanical agglomeration of mechanical agitation or frozen fat method, etc., wherein the polymer agglutinating agent used in the chemical fertilizer method can use butyl acrylate-methacrylic acid copolymer.

In the method for producing a rubber graft copolymer obtained by bulk or solution polymerization, for example, 2 parts by weight to 25 parts by weight of the diene rubber may be previously dissolved in 98 parts by weight to 75 parts by weight of the monomer mixture and In the solvent to be selected, the monomer mixture may include 40 parts by weight to 90 parts by weight of the fourth styrene monomer, and 10 parts by weight to 60 parts by weight based on 100 parts by weight of the monomer mixture. a tetraacrylonitrile-based monomer and 0 parts by weight to 40 parts by weight of a second other copolymerizable monomer, and then pumping the resulting solution into a reaction tank for graft polymerization, and an appropriate chain shift may be added during the reaction. A transfer agent, such as a third-dodecyl mercaptan, to control the molecular weight of the polymer, and the reaction tank used may be a combination of a plurality of tanks connected in series or in parallel, preferably a kettle-shaped reaction tank with a strong agitator. The solvent may be toluene, xylene, ethylbenzene, methyl-ethyl ketone, ethyl acetate or the like.

The diene rubber used in the bulk or solution polymerization method is preferably obtained by an anionic polymerization method, such as butadiene rubber, isoprene rubber, chloroprene rubber, butadiene-propylene. Nitrile rubber, butadiene-styrene rubber, etc., wherein butadiene rubber has high cis (Hi-Cis) content and low cis (Los-Cis) content; in high cis rubber, cis ( Cis)/Vinyl has a typical weight composition of (94% to 98%) / (1% to 5%), and the rest of the composition is a trans structure with a Mooney viscosity of 20 to 120. The molecular weight range is preferably from 100,000 to 800,000. In the low cis rubber, the typical weight composition of cis/vinyl is (20% to 40%) / (1% to 20%), and the rest is a trans structure with a Mooney viscosity of 20 to 120 rooms. In the diene rubber graft copolymer of the block or solution polymerization method of the present embodiment, a suitable rubber is preferably a butadiene rubber.

a rubber graft copolymer obtained by polymerization in a bulk or solution polymerization method, wherein the rubber particles have a weight average particle diameter of, for example, 0.6 μm to 10 μm, preferably 0.9 μm to 7 μm, which is obtained by the bulk or solution polymerization method. The rubber graft copolymer has a rubber content of, for example, 4% by weight to 25% by weight, preferably 8% by weight to 15% by weight.

The rubber graft copolymer of the present embodiment may be used in addition to the rubber graft copolymer of the emulsion polymerization method or the rubber graft copolymer of the bulk (or solution) polymerization method. Forming a bimodal or trimodal distribution, wherein the bimodal distribution is as follows: (1) a weight average particle diameter of 0.2 μm to 0.8 μm (emulsification polymerization), a weight average particle diameter of 0.6 μm to 10 μm (block or solution polymerization); Or (2) a weight average particle diameter of 0.05 μm to 0.18 μm (emulsification polymerization), and a weight average particle diameter of 0.6 μm to 10 μm (block or solution polymerization).

The three-peak type distribution is, for example, a weight average particle diameter of 0.05 μm to 0.15 μm (emulsification polymerization), a weight average particle diameter of 0.17 μm to 0.8 μm (emulsification polymerization), and a weight average particle diameter of 0.25 μm to 7.0 μm (block or solution). polymerization).

The method for testing the weight average particle diameter of the rubber particles is to dye the resin with osmium tetroxide (OsO ₄ ), and then take a transmission electron microscope to take about 1000 pieces of rubber dispersed particles in the photograph. The particle size is determined by the following formula:

In the above formula, n is the number of rubber particles having a "rubber particle diameter D".

The type of the fourth styrene monomer used in the rubber graft copolymer of the present embodiment is the same as that of the second styrene monomer described above, and therefore will not be described again, wherein the fourth styrene monomer is benzene. Ethylene or α-methylstyrene is preferred.

The type of the fourth acrylonitrile-based monomer used in the rubber graft copolymer of the present embodiment is the same as that of the second acrylonitrile-based monomer described above, and therefore, the fourth acrylonitrile-based monomer is propylene. Nitrile is preferred.

The second other copolymerizable monomer used in the rubber graft copolymer of the present embodiment is the same as the first other copolymerizable monomer described above, and therefore will not be described again, wherein the second other copolymerizable monomer is Methyl methacrylate, butyl methacrylate, and nitrogen-phenylmaleimide are preferred.

The thermoplastic resin composition of the present embodiment may be added with various additives as needed, such as an antioxidant, a lubricant, an ultraviolet absorber, a UV stabilizer, a charge inhibitor, a colorant, etc., and the addition time may be modified in a divergent copolymer or rubber. The polymerization stage or the kneading stage of the styrene resin.

A molded article according to another embodiment of the present invention is formed of the thermoplastic resin composition as described above. The preparation method of the molded article is not particularly limited, and thermoforming, vacuum forming, or a combination of the above processes may be employed. The thermoforming and vacuum forming can be carried out in a known manner and will not be described again.

The thermoplastic resin composition of the present invention will be more specifically described below with reference to several experiments. Although the following experiments are described, the materials used, the amounts and ratios thereof, the processing details, the processing flow, and the like can be appropriately changed without departing from the scope of the invention. Therefore, the invention should not be construed restrictively based on the experiments described below.

The average radius of gyration and the weight average molecular weight of each component obtained by the following experiment were determined as follows:

<average radius of gyration>

Multi-angle laser (DAPN8+) multi-angle laser manufactured by Wyatt Technology Co., Ltd. using Gel Permeation Chromatography (GPC) manufactured by Waters Co., Ltd. Light scattering, MALLS and viscoStar-II viscometer were measured under the following conditions: MZ-Gel SDplus linear 5 μm, 300 mm x 8.0 mm, mobile phase: THF (flow rate 0.5 ml/min).

<weight average molecular weight>

Gel Permeation Chromatography (GPC) manufactured by Waters Co., Ltd., with differential refractive index detector (Waters RI-2414) and ultraviolet visible light detector (Waters PDA-2996) The measurement conditions were as follows: column: MZ-Gel SDplus linear 5 μm, 300 mm x 8.0 mm, mobile phase: THF (flow rate 0.5 ml/min).

Each of the components used in the experimental examples and comparative examples was prepared as follows:

Divided copolymer (BHAS-1) Synthesis

In the reactor, 0.3 parts by weight of tetrakis(3-mercaptopropionic acid) pentaerythritol, 71 parts by weight of styrene monomer, 29 parts by weight of acrylonitrile monomer, 150 parts by weight of deionized water, and 0.4 parts by weight of Calcium phosphate, 0.03 parts by weight of a carboxyl anionic surfactant, 0.01 parts by weight of a polyoxyethylene alkyl phosphate, and 0.001 parts by weight of a 2,2'-azobisisobutyronitrile starter are mixed and added to one In the reactor. The reactor was completely sealed. The mixture was thoroughly stirred to disperse. Heating was carried out to raise the reaction temperature to 75 ° C and the polymerization was carried out for 3 hours. After the end of the polymerization, the reactor was cooled to room temperature to terminate the reaction. The obtained product was washed, dehydrated and dried to obtain a divergent copolymer (BHAS-1) having a weight average molecular weight of 3.57 million and an average radius of gyration [R (avg)] of 80.7 nm.

the first Styrene - Acrylonitrile copolymer (A-1) Preparation

68 parts by weight of styrene, 32 parts by weight of acrylonitrile, and 8 parts by weight of ethylbenzene were mixed, and then mixed with 0.01 part by weight of the third-dodecyl mercaptan, and at a flow rate of 35 kg/hr. The mixture was continuously fed to a fully mixed continuous reactor having a volume of 40 liters, an internal temperature of 145 ° C, a pressure of 4 kg/cm ² and an overall conversion of about 55%.

After the completion of the polymerization, the obtained copolymer solution was heated by a preheater, and volatile substances such as unreacted monomers and solvents were removed in a vacuum degassing tank. Next, the obtained polymer melt is subjected to granulation to obtain a first styrene-acrylonitrile-based copolymer (A-1) having a weight average molecular weight of 210,000 and a styrene monomer unit content of 72%, acrylonitrile. The monomer unit content was 28%.

second Styrene - Acrylonitrile copolymer (A-2) Preparation

55 parts by weight of styrene, 45 parts by weight of acrylonitrile, and 8 parts by weight of ethylbenzene were mixed and continuously supplied to a fully mixed continuous reactor at a flow rate of 35 kg/hr, wherein the volume of the reactor was For 40 liters, the internal temperature was maintained at 145 ° C, the pressure was maintained at 4 kg / cm ² , and the overall conversion rate was approximately 55%.

After the completion of the polymerization, the obtained copolymer solution was heated by a preheater, and volatile substances such as unreacted monomers and solvents were removed in a vacuum degassing tank. Next, the obtained polymer melt is subjected to granulation to obtain a second styrene-acrylonitrile-based copolymer (A-2) having a weight average molecular weight of 140,000 and a styrene monomer unit content of 67%, acrylonitrile. The monomer unit content was 33%.

Rubber graft copolymer (B-1) Preparation

150.00 parts by weight of 1,3-butadiene, 15.00 parts by weight of potassium persulfate solution (concentration 1 wt%), 2.00 parts by weight of potassium oleate, 0.13 parts by weight of ethylene glycol dimethacrylate and 190.00 The parts by weight of distilled water was reacted at a reaction temperature of 65 ° C for 14 hours to obtain a rubber emulsion having a weight average particle diameter of 0.1 μm (conversion ratio of about 94%, solid content of about 36%).

90.00 parts by weight of n-butyl acrylate, 10.00 parts by weight of methacrylic acid, 0.50 parts by weight of potassium persulfate solution (concentration: 1 wt%), 0.50 parts by weight of sodium lauryl sulfate solution (concentration: 10 wt%) 1.00 parts by weight of n-dodecyl mercaptan and 200.00 parts by weight of distilled water were reacted at a reaction temperature of 75 ° C for 5 hours to obtain a carboxylic acid group-containing polymer flocculant emulsion having a conversion of about 95% and a pH of 6.0. .

Thereafter, 3 parts by weight (dry weight) of a carboxylic acid group-containing polymer aggregating agent is used to ferment 100 parts by weight of the rubber latex, and the obtained rubber emulsion has a pH of 8.5 and a rubber weight average particle diameter of about 0.3. Mm.

Further, 300.0 parts by weight of the above-mentioned enlarged rubber emulsion (dry weight), 75.0 parts by weight of styrene, 25.0 parts by weight of acrylonitrile, 2.0 parts by weight of thirteen-dodecyl mercaptan, and 3.0 parts by weight of isopropyl Benzene hydroperoxide, 3.0 parts by weight of ferrous sulfate solution (concentration 0.2 wt%), 0.9 parts by weight of sodium formaldehyde sulfoxylate solution (concentration: 10 wt%), and 3.0 parts by weight of ethylenediaminetetraacetic acid solution (concentration 0.25) Gt%), the above-mentioned hypertrophized rubber emulsion is graft-polymerized with a styrene acrylonitrile copolymer to produce a rubber graft copolymer. The prepared rubber graft copolymer emulsion is coagulated with calcium chloride, and then dehydrated and dried to less than 2% to obtain a desired rubber graft copolymer (B-1), and the average weight of the rubber particles is The particle size was 0.31 μm and the rubber content was 75% by weight.

Rubber graft copolymer (B-2) Preparation

6.6 parts by weight of polybutadiene (available from Asahi Kasei Co., Ltd. under the trade name Asadene 55AS) was completely dissolved in 74.4 parts by weight of styrene and 25.6 parts by weight of propylene with 0.08 parts by weight of benzamidine peroxide as a starting agent. Nitrile and 30 parts by weight of ethylbenzene to form a feed solution, and then the feed solution is continuously fed into a first reactor having a volume of 45 liters, the reaction temperature is 100 ° C, and a cooling circulation tube is disposed in the reactor. a spiral agitator having a stirring rate of 150 rpm, a monomer conversion rate of 15% in the first reactor, continuously taking out the mixture after the first reactor reaction, and sequentially feeding the second, third, and fourth reactions. In the apparatus, 0.1 part by weight of the third-dodecyl mercaptan is simultaneously added to the third reactor, and the reverse rotation phenomenon is generated in the second reactor, and the second, third, and fourth reactor devices are first and The reactor is the same, but the reaction temperature is 105 ° C, 110 ° C, 125 ° C, and the stirring rate is 270 rpm, 150 rpm and 110 rpm. When the conversion ratio of the hydrazine mixture reaches 60%, the mixture is taken out and sent to the devolatilizer. Remove unreacted monomer Volatile components, after which extrusion granulator, to obtain a particulate rubber graft copolymer (B-2), a weight average particle diameter of the rubber particles was 0.95 m, the rubber content of 10 wt%.

Experimental example 1 To the experimental example 6 Preparation

37.59 parts by weight of the first styrene-acrylonitrile based on 100 parts by weight of the rubber-modified styrene resin (A-1, A-2, B-1 and B-2) in a dry state Copolymer (A-1), 37.59 parts by weight of a second styrene-acrylonitrile copolymer (A-2), 17.73 parts by weight of a rubber graft copolymer (B-1), and 7.09 parts by weight of a rubber joint The branched copolymer (B-2) was added to a biaxial extruder (Model: ZPT-25, manufacturer: Zeji Industry Co., Ltd.), and a ratio of a pair of divergent copolymers (BHAS-1) according to the table was added. Further, 2.0 parts by weight of a slip agent was added and kneaded at a kneading temperature of 220 ° C, followed by extrusion with a biaxial extruder, and the thermoplastic resin compositions of Experimental Examples 1 to 6 were obtained.

The elongational viscosity and shear viscosity of each of the thermoplastic resin compositions prepared in the above experiment were measured by the following measurement methods, and the results are shown in Table 1.

<Elongation viscosity>

A rheometer (Rheometer ARES-G2) manufactured by TA Instruments was used at a temperature of 170 ° C and a shear rate of 0.5 / s.

<Shear viscosity>

A rheometer (Rheometer ARES-G2) manufactured by TA Instruments was used at a temperature of 230 ° C and a shear rate of 100 / s.

Table I A-1: First styrene-acrylonitrile copolymer A-2: Second styrene-acrylonitrile copolymer B-1: Rubber graft copolymer B-2: Rubber graft copolymer BHAS-1: Divided copolymer RC%: total rubber content

Table 1 (continued)

In the results of Table 1, the thermoplastic resin compositions of Experimental Examples 1 to 6 were added with two specific ratios of styrene-acrylonitrile copolymers in addition to the divergent copolymer, respectively, containing weight average molecular weights. a first styrene-acrylonitrile-based copolymer (A-1) of 210,000 and a second styrene-acrylonitrile-based copolymer (A-2) having a weight average molecular weight of 140,000; wherein, based on the first The total content of the styrene-acrylonitrile-based copolymer (A-1) and the second styrene-acrylonitrile-based copolymer (A-2) is 100% by weight, and the first styrene-acrylonitrile-based copolymer (A- The content of 1) and the content of the second styrene-acrylonitrile-based copolymer (A-2) were each 50% by weight, so that the thermoplastic resin compositions of Experimental Examples 1 to 6 had relatively low shear viscosities. With excellent elongational viscosity, both sheeting and vacuum formability can be considered.

In detail, Experimental Examples 1 to 6 are based on 100 parts by weight of the rubber-modified styrene-based resin, and the content of the branched copolymer is limited to a range of 1.5 parts by weight to 8 parts by weight, wherein Experimental Example 1 Further, in Experimental Example 4, the content of the divalent copolymer contained was further limited to a range of from 2.5 parts by weight to 6 parts by weight, which exhibited a lower shear viscosity than the shear viscosity of Experimental Example 6.

On the other hand, in the prior art, the shear viscosity increases as the content of the divergent copolymer increases, so the properties of the plate are not satisfactory; however, from the results of the first experimental example 1 to the experimental example 5, It is shown that the present invention can ameliorate the aforementioned disadvantages. For example, in Experimental Example 4 containing 6 parts by weight of the divalent copolymer, the shear viscosity was almost the same as that of Experimental Example 5 containing 2 parts by weight of the divalent copolymer, but the elongational viscosity of Experimental Example 4 was significantly higher than that of the experimental example. 5 excellent.

Comparative example 1 To comparative example 7 Preparation

The preparation methods of the thermoplastic resin compositions of Comparative Examples 1 to 7 were the same as those of Experimental Example 1 to Experimental Example 6, except that Comparative Examples 1 to 7 were based on the ratios of the components listed in Table 2. For the preparation, the measurement methods of the shear viscosity and the elongational viscosity were the same as described above and the results are shown in Table 2.

Table II A-1: First styrene-acrylonitrile copolymer A-2: Second styrene-acrylonitrile copolymer B-1: Rubber graft copolymer B-2: Rubber graft copolymer BHAS-1: Divided copolymer RC%: total rubber content

Table 2 (continued)

In the results of Table 2, the thermoplastic resin compositions of Comparative Examples 1 to 6 also used a divergent copolymer and two specific ratios of styrene-acrylonitrile copolymer, but shear viscosity and elongational viscosity. The test results were significantly worse than those of Experimental Example 1 to Experimental Example 6. For example, in Comparative Example 1 to Comparative Example 3, the total content of the first styrene-acrylonitrile-based copolymer (A-1) and the second styrene-acrylonitrile-based copolymer (A-2) is 100% by weight. The content of the first styrene-acrylonitrile-based copolymer (A-1) is 40% by weight, and the content of the second styrene-acrylonitrile-based copolymer (A-2) is 60% by weight, that is, the first The content of the styrene-acrylonitrile-based copolymer (A-1) is less than 45% by weight, and the content of the second styrene-acrylonitrile-based copolymer (A-2) is more than 55% by weight, so even a divergent copolymer The content of the film was in the range of 1 part by weight to 10 parts by weight, and the elongational viscosity of Comparative Example 1 to Comparative Example 3 was still poor.

Further, Comparative Example 4 to Comparative Example 6 are based on the total content of the first styrene-acrylonitrile-based copolymer (A-1) and the second styrene-acrylonitrile-based copolymer (A-2) being 100% by weight. %, the content of the first styrene-acrylonitrile-based copolymer (A-1) is 60% by weight, and the content of the second styrene-acrylonitrile-based copolymer (A-2) is 40% by weight, that is, the first The content of the monostyrene-acrylonitrile-based copolymer (A-1) is more than 55% by weight, and the content of the second styrene-acrylonitrile-based copolymer (A-2) is less than 45% by weight, so even if the copolymerization is branched The content of the substance was in the range of 1 part by weight to 10 parts by weight, and the shear viscosity measured in Comparative Example 4 to Comparative Example 6 exhibited a high shear viscosity with respect to the experimental example.

On the other hand, the experimental examples and the comparative examples in which the same weight parts of the divalent copolymer were used, for example, Experimental Example 5, Comparative Example 1 and Comparative Example 4 were each used in an amount of 2 parts by weight of the divalent copolymer, and Experimental Example 5 and In Comparative Example 1, although the shear viscosity of Comparative Example 1 was slightly smaller than the shear viscosity of Experimental Example 5, Experimental Example 5 had a relatively excellent elongational viscosity; and in Experimental Example 5 and Comparative Example 4, Comparative Example 4 Although the elongational viscosity is increased, the shear viscosity is also increased. In contrast, in Experimental Example 5, the elongational viscosity is increased, and the shear viscosity is also considered, so Experimental Example 5 is compared with Comparative Examples 1 and 4. It has good boarding property and vacuum formability.

Further, in Experimental Example 2, Comparative Examples 3, 6, and 7, 3 parts by weight of a divalent copolymer was used, wherein the first styrene-acrylonitrile copolymer (A-1) of Comparative Example 3 and Comparative Example 6 was used. The content of the second styrene-acrylonitrile-based copolymer (A-2) exceeds the range of 45% by weight to 55% by weight, so the shear viscosity and the elongational viscosity are inferior to those of Experimental Example 2; and Comparative Example 7 Although the elongational viscosity was increased by the divalent copolymer, Comparative Example 7 used only a single styrene-acrylonitrile copolymer, so that the shear viscosity of the thermoplastic resin composition could not be effectively reduced, which was inferior in processing and molding applications. Experimental Example 2.

As described above, the thermoplastic resin composition of the present invention comprises a divergent copolymer and a rubber-modified styrene resin. Wherein the divergent copolymer comprises a tetrathiol compound unit, a first styrene monomer unit, and a first acrylonitrile monomer unit; and the rubber modified styrene resin comprises 70% by weight to 90% by weight. a continuous phase formed of a styrene copolymer and a dispersed phase formed by 10% by weight to 30% by weight of rubber particles, wherein the styrene copolymer comprises a first styrene-acrylonitrile copolymer and a second styrene- The acrylonitrile-based copolymer, the weight average molecular weight of the first styrene-acrylonitrile copolymer is different from the weight average molecular weight of the second styrene-acrylonitrile copolymer; based on the first styrene-acrylonitrile copolymer and The total content of the second styrene-acrylonitrile-based copolymer is 100% by weight, and the content of the first styrene-acrylonitrile-based copolymer is 45% by weight to 55% by weight, and the second styrene-acrylonitrile-based copolymer The content is from 45% by weight to 55% by weight. The thermoplastic resin composition of the present invention is obtained by using a divergent copolymer in a thermoplastic resin composition and using a first styrene-acrylonitrile-based copolymer and a second styrene-acrylonitrile-based copolymer which are mixed in a specific ratio. Both sheeting and vacuum formability can be considered.

While the present invention has been described above by way of example, it is not intended to limit the scope of the present invention, and it is possible to make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

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Claims (14)

A thermoplastic resin composition comprising: a divalent copolymer comprising a tetrathiol compound unit, a first styrene monomer unit and a first acrylonitrile monomer unit; and a rubber modified styrene resin comprising: a continuous phase formed by 70% by weight to 90% by weight of the styrene-based copolymer; and a dispersed phase formed by 10% by weight to 30% by weight of the rubber particles, wherein the styrene-based copolymer comprises the first styrene-propylene a nitrile-based copolymer and a second styrene-acrylonitrile-based copolymer, wherein the weight average molecular weight of the first styrene-acrylonitrile-based copolymer is different from the weight average molecular weight of the second styrene-acrylonitrile-based copolymer; The content of the first styrene-acrylonitrile-based copolymer is 45% by weight based on the total content of the first styrene-acrylonitrile-based copolymer and the second styrene-acrylonitrile-based copolymer being 100% by weight. 55 wt%, the content of the second styrene-acrylonitrile-based copolymer is from 45% by weight to 55% by weight. The thermoplastic resin composition according to claim 1, wherein the first styrene-acrylonitrile copolymer has a weight average molecular weight of 180,000 to 240,000, and the second styrene-acrylonitrile copolymer The weight average molecular weight is 110,000 to 170,000. The thermoplastic resin composition according to claim 1, wherein the first styrene-acrylonitrile-based copolymer comprises 71% by weight to 74% by weight of the second styrene monomer unit and 26% by weight to 29% by weight of the second acrylonitrile-based monomer unit, the second styrene-acrylonitrile-based copolymer comprising 60% by weight to 69% by weight of the third styrene-based monomer unit and 31% by weight to 40% by weight The third acrylonitrile monomer unit. The thermoplastic resin composition according to claim 1, wherein the content of the conjugated copolymer is from 1 part by weight to 10 parts by weight based on 100 parts by weight of the rubber-modified styrene resin. The thermoplastic resin composition according to claim 4, wherein the content of the condensed copolymer is from 1.5 parts by weight to 8 parts by weight based on 100 parts by weight of the rubber-modified styrene resin. The thermoplastic resin composition according to claim 5, wherein the content of the conjugated copolymer is from 2.5 parts by weight to 6 parts by weight based on 100 parts by weight of the rubber-modified styrene resin. The thermoplastic resin composition according to claim 1, wherein the divergent copolymer has an average radius of gyration of from 75 nm to 110 nm. The thermoplastic resin composition according to claim 7, wherein the divergent copolymer has an average radius of gyration of from 80 nm to 100 nm. The thermoplastic resin composition according to claim 1, wherein the divalent copolymer has a weight average molecular weight of 1,000,000 to 7,000,000. The thermoplastic resin composition according to claim 9, wherein the divalent copolymer has a weight average molecular weight of 2,000,000 to 5,000,000. The thermoplastic resin composition according to claim 1, wherein the tetrathiol compound unit is formed of a tetrathiol compound. The thermoplastic resin composition according to claim 11, wherein the tetrathiol compound is selected from the group consisting of pentaerythritol tetrakis (3-mercapto propionate) and tetrakis(2-mercapto). Pentaerythritol tetrakis (2-mercapto ethanate), pentaerythritol tetrakis (4-mercapto butanate), tetrakis(5-mercaptovaleric acid) pentaerythritol [pentaerythritol tetrakis (5) -mercapto pentanate)] and at least one of the group consisting of pentaerythritol tetrakis (6-mercapto hexanate). The thermoplastic resin composition according to claim 12, wherein the tetrathiol compound is pentaerythritol tetrakis (3-mercapto propionate). A molded article is formed from the thermoplastic resin composition according to any one of claims 1 to 13.